Astronomic dial for time switches



Nav. 17, 1936. i C, HoLTz 2,060,991

ASTRONOMIC DIAL FOR TIME SWITCHES Filed May l2, 1953 2 Shasta-Sheet 1 Inf/@n for; Fedefc/f Cif/70 ZZZ.

f M) 5mg/l rig/t? Nov; 17, 1936. F C, HOLTZ 2,060,991

ASTRONOMIC DIAL FOR TIME SWITCHES Filed May 12, 19153 2 Sheets-Sheet 2 Nil' I' H1111- Z/ lmtllnfg'l'llul lill 37 am.. A

Patented Nov. 17, y1.936

PATENT OFFICE ASTRONOMIC DIAL FOR TIME SWITCHES Frederick c. Holtz, -springfield, 111., assignor to Sangamo Electric Company, Springfield, Ill., a

corporation of Illinois Application May 12, 1933, Serial No. 670,704

11 Claims.

The present invention relates to astronomie dials for time switches and the like, such as have the utility of turning` on and off electric signs, electric lights, etc., according to the rising and setting of the sun. In their general construction, devices of this type comprise a dial head which is rotated by a suitable clock or other timing mechanism at a speed such that the dial head makes one complete revolution every twentyfour hours. The electrical switch which is associated with this dial head is actuated by two switch actuators in the form of knobs, studs or the like, which project from the dial head at spaced points and are adapted to engage the switch tripping parts. One such switch actuator closes the electric switch, as at sunset, and the other switch actuator opens the electric switch, as at sunrise. These two switch actuators are carried by the dial head to revolve therewith, and are also capable of shifting movement in angular paths concentric of the dial head, whereby they may be advanced or retarded with reference to the hour marks or other datum points on the dial head. For a given day of the year at a given latitude, these two switch actuators will occupy certain positions with respect to the hour marks or datum points on the dial head. With the change of the seasons, said switch actuators will be moved with an advancing or recessional movement relatively to the aforesaid positions, with the change in time of sunrise and sunset. This automatic shifting of the positions of the switch actuators is effected by cams which are mounted within the dial head and are carried o thereby, but which are arranged to have a relatively slow rotative movement with respect to the rotating dial head.

One of the principal objects of the invention is to provide improved motion transmitting mechanism for transmitting motion from the cams to the switch actuators, i. e., shifting the angular positons of the switch actuators relatively to the dial head in accordance with the change of angular position of the cams relatively to the dial head. Each switch actuator is secured to the outer end of a swinging arm which is preferably mounted for oscillation about the hub of the dial head. Associated with each cam is a cam follower which is caused to move inwardly and outwardly in following the different radii of the cam. One of the specic features of improvement of my invention resides in the manner of transmitting motion from the cam follower to said swinging arm. This is done by a gear sector and pinion, the gear sector preferably constituting an extension of the cam follower, and the pinion being secured to the hub of the swinging arm. The sector and pinion connection insures that the movement transmitted from the cam follower to the switch actuator shall be at a constant ratio throughout the entire range of movement of the follower and switch actuator. This is advantageous over the use of a link connection between the cam follower and swinging arm, where the shifting Aof the pivot centers of the connecting link, particularly adjacent to the limits of movement of the switch actuator, is likely to change the ratio of the movement transmitted from the cam follower to the switch actuator. Where a high degree of accuracy of timing control is desired, this variation of the ratio of movement must be compensated for by a corresponding variation in the contour of the cam, which complicates the matter of properly shaping the cam. In the present construction, wherein a constant ratio of movement is obtained by the sector and pinion arrangement, this is avoided and the only consideration in the proper shaping of the cam is the seasonal change of sunrise and sunset corresponding to the latitude in which the instrument is used.

'I'he sector and pinion construction is also advantageousin simplifying the assembly of the device, and in providing a construction which is simple and inexpensive to manufacture.

Another object of the invention is to provide an improved construction in which the cams are readily accessible, so that they can be interchanged with facility in adapting the device to use in different latitudes or under different operating conditions.

Another object of the invention is to provide a construction including an improved arrangement of guide means for guiding the motion of the swinging arms which carry the switch actuators.

Other objects and advantages of the invention will appear from the following detail description of a preferred embodiment of the invention. This embodiment is disclosed as for the purpose of performing switching operations in accordance with the rising and setting of the sun, but it will be understood that the invention is not necessarily restricted to such use, as the timed intervals or schedule may be changed to agree with anyother predetermined arrangement for a calendar year.

In the accompanying drawings:-

Figure 1 is a front elevational view of the improved dial embodying my invention, this view illustrating, diagrammatically, certain switch parts to be actuated by the dial;

Figure 2 is a side or edge elevational view, as viewed from the bottom of Figure l;

Figure 3 is a transverse sectional view, corresponding to a section taken approximately on the plane of the line 9 2 of Figure 4;

Figure 4 is an axial sectional view taken approximately on the plane of the line .-4 of Figure 3;

Figure 5 is a detail -perspective view illustrating the sector and pinion arrangement of motion transmitting mechanism operative between each cam and the swinging arm bearing the associated switch actuator;

Figure 6 is a perspective view of the cam assembly; and

Figure 'I is a detail perspective view of one of the swinging arms with the pinion secured thereto The dial head is designated II in its entirety, and the On and Oif switch actuators are designated I2 and Il, respectively. These two switch actuators are disposed in different transverse planes of the dial head, as shown in Figure 2. The switch assembly. designated Il, may be of any desired construction. In the exemplary construction illustrated is a diagrammatic representation of the general type disclosed in the copending application of Wilmeth and Keyes, Serial No. 616,180, illed June 9, 1932. Briefly described, these switch parts comprise the stationary contact I5, the movable contact Il, and the three switch tripping levers I1, I9 and I9. The lever I9 carries a roller 20 which, in one movement of said lever, is adapted to press the switch contacts apart. 'I'he lever I1 comprises an extension arm I1a carrying a pivot pin i1b, and the lever I9 is pivotaiiy mounted on said pin. The lever I8 comprises an extension arm Ila, and the lever I9 comprises an extension arm I9a, and extending between these extension arms is a tension spring 2I. A shoulder I9b on the extension arm I9a is adapted to engage a shoulder IIb on the lever I 9 when the switch is in closed position. 'I'he spring 2I tends to swing the arm I9 into a switch opening position, which is permitted when the arm I8 is actuated to draw its shoulder IIb out from in back of the shoulder I9b on the lever I9. The lever I1 is in the path' of the switch actuator I2, and the lever I9 is in the path of the switch actuator I3, whereby these levers are engaged successively by the switch actuators in the rotation of the dial head II.` In the switch closing operation, the actuator I2 engages the lever I1 and swings it to carry the lever I9 outwardly for restoring the shoulder IIb in position to engage the shoulder I9b. When the lever I1 snaps oil the actuator I2, it is drawn back by a spring 29 against a stop 2l, such motion acting through the lever I9 and shoulders I8b, I9b to osciliate the lever I9 back to switch closing position. In the switch opening operation, the engagement of the actuator Il against the lever Il draws the shoulder IIb out from behind the shoulder I9b, permitting the spring 2| to oscillate the lever I9 to switch opening position. `It will be understood that any other type of switch may be used. the above described switch being shown merely for illustrative purposes.

Referring to Figure 4, the dial head is secured to a rotating shaft 25 which is driven by a clock train or any other suitable timing mechanism. 'I'his shaft is arranged to rotate exactly one revolution every twenty-four hours. The dial head comprises a main circular mounting plate 29, to the outer face of which is detachabiy secured a marked disc 21. The face of this disc has inscribed thereon the numbered markings 21a designating the 24 hours of the day. preferably subdivided into fifteen minute intervals, and also has inscribed thereon the "Day" and "Night marks 21h, the directional arrow 21c, and the latitude marking 21d. Cut through this face disc and through the mountingplate 20 is a sight window 29 through which the indications on the month wheel can be viewed. Two screws 29 pass through openings in the marked disc 21 and thread into the mounting plate 2l for fixedly securing-the disc to the plate. The mounting plate is secured to a hub ll which fits over the drive shaft 25, the rear end of said hub abutting against a shoulder 25a on the drive shaft. Any suitable retaining device l2, such as a transverse pin or nut, coacts between the front end of the hub 3i and said shaft for retaining the dial head on the shaft, the operative connection being such as to compel rotation of the dial head with the shaft. The back side of the mounting plate 26 abuts against the shoulder Sla on the hub II, and this mounting plate, together with the disc 21, are clamped between said shoulder and a nut 22 which screws inwardly over the threaded outer end of the hub. A suitable set screw Il may be provided for holding the nut Il in its tightened position. In the event that the cam assembly is changed for a different latitude, the marked disc 21 can be substituted with another disc having the proper latitude marking 21d by merely removing the screws 29 and nut 22, whereupon the disc 21 may be lifted oil the mounting plate 29 and a new disc substituted..

Referring to Figure 3, four spacing studs or posts 36, 31, 3l and 29 have their front ends riveted in the mounting plate 2l and project rearwardly therefrom, these posts being arranged in pairs. Screws 39a, 31a, etc., thread into the outer ends of these posts (see screw 31a in Figure 4) and secure spacing sleeves and other parts of the assembly on these posts. An arcuate bridge bar 4I is secured in the outer ends of one pair of posts 26, 31, and a similar arcuate bridge bar 42 is secured to the outer ends of the other pair of posts 28, 39. A pintle 42 for the two cam followers is supported between the mounting plate 26 and the bridge bar 4I, and a pintle 44 for the star wheel (to be later described) is secured between the mounting plate 26 and the other bridge bar 42. As will be later described, other pairs of arcuate bars extend between these posts for denlng guide-ways for the swinging arms that support the switch actuators.

The month wheel It is rotatably mounted directly in back of the plate 29 and disc 21, where the month indicia 46a inscribed on this wheel can be viewed through the sight window 2l. Preferably, the month intervals are subdivided into five-day intervals, with the month intervals of varying angular extent corresponding to the different lengths of the months. 'I'hese indicia 46a cooperate with an index pointer 29a flxedly secured in the sight window 29. The periphery of the month wheel 46 is provided with gear teeth 6b which mesh with a driving pinion 41. This pinion is secured to a pintle I8 which has its front end journaied in the mounting plate 29, A large spur gear I9 is also secured to the pintle and drives the pinion 41. A light spring arm 5I is secured to the adjacent mounting post 38 and has its resilient end bearing against the spur gear 49 for holding the front end of the pintle 48 in its bearing in the mounting plate 26. Meshing with the large gear wheel 48 is a spur pinion 52 which is secured to the pintle 44. A five-pronged star wheel 63 is secured fast to the rear end of this pintle, beyond the bridge bar 42. The arms or fingers of this star wheel project from the periphery of the dial head, in position to engage with a stationary pin 54 which is xedly secured to any stationary mounting structure adjacent to the dial head. In each revolution of the dial head, occurring once in 24 hours, one of the ngers of this star wheel is engaged by the pin 54 and the wheel is rotated clockwise with respect to the dial head, which is rotating counterclockwise, as viewed in Figure l. The pin 54 is disposed so that it has no interference with the switch actuators I2, I3 or with the swinging arms supporting the latter. Rotating with the star wheel is a pentagonal detent boss 55 against which the free end of a leaf spring 56 bears for yieldingly holding the star wheel and its pinion 52 in each of its advanced positions. The leaf spring 56 is coiled about the spacing post 38 and is pressed inwardly by a pin 51. It will be observed from the foregoing that the month wheel is carried by the dial head in the sense that the major portion of the rotative movement of the month wheel is in the same direction as the dial head; but it will also be noted that each time that an arm of the star wheel 53 engages the stop pin 54, an angular motion is imparted to the month wheel which is backward with respect to the direction of rotation of the dial head, whereby'the month wheel has an intermittent motion relatively to the dial head, which is retrogressional. 'I'he invention is not necessarily limited to this relative motion being retrogressional, because the relative motion might be in a forward direction,

Rotatably mounted on the hub 3|, directly in back of the month wheel 46, is the cam assembly 6I, comprising a sleeve 6Ia, an annular flange 6 Ib radiating from this sleeve, and two cam discs 6Ic and Gld. The cam discs are mounted at opposite sides of the annular flange 6Ib, and are rigidly secured thereto by rivets 62 passing through the cams and through the flange. The month wheel 46 is secured to the cam sleeve 6Ia by screws 63 and pins 64, which are in such relation as to preclude the possibility of the month wheel being secured to the cam hub in any other than the proper angular relation. For example, referring to Figure 6, the screws 63 thread into tapped holes 63a in the end of the cam hub, and the two pins 64 project from the end of the cam hub in such relation to the screw holes as to be capable of reception in pin sockets in the month wheel only when the wheel and cam hub are in one predetermined angular relation. Thus, all possibility of erroneous assembly of these two parts is avoided. The end of cam hub 6Ia bears against the washer 66, which in turn bears against an annular shoulder 3Ib projecting from the inner portion of the main hub 3|. It will be clear that the two cams 6Ic and 6Id rotate in direct synchronism with the month wheel 46.

The two cams are disposed between the two swinging arms 68 and 69, which carry the switch actuators I2 and I3. The arm 68 has a ring like inner end which is secured to a hub or pinion ring 68a which-is rotatably mounted on the cam hub 6Ia in rear of the cam disc 6Ic. Likewise, the swinging arm 69 has a ring-like inner end which is secured to a hub or pinion ring 69a, the latter being rotatably mounted on. the cam'hub forwardly of the front cam 6Ie. As shown in Figure 4, each pinion ring is preferably secured to its swinging arm by providing the ring with a reduced neck portion which is extended through the ring-like inner end of the arm and is then peened over on the outer side of the arm. The outer ends of the swinging arms are guided in their oscillating motion between pairs of arcuate guide bars 1I, 12. 'I'he ends of the guide bars 1I are mounted on the two supporting posts 36 and 38, with suitable spacing Washers interposed between the ends of said bars or plates, and the other two guide bars 12 have their ends mounted on the other two posts 31, 39 with suitable spacing washers intervening, these two sets of guide bars being offset fore and aft, as illustrated in Figure 4, corresponding to the fore and aft offset relation between the swinging arms 68 and 69. The guideways defined between each pair of these bars prevent any possibility of the swinging arms being bent by any force acting against the arms or against their switch actuators in a fore and aft direction, and insure that the two switch actuators I2 and I3 will always engage with their proper switch tripping arms I1 and I8.

As clearly shown in Figures 3 and 5, each of the rings 68a and 69a are provided with gear teeth 68h, 69h. 'I'hese teeth need only extend over a limited portion of the periphery of each ring, although they might be extended around the entire ring, if desired. Coacting with these toothed portions are two cam followers 15, 16 which are approximately J-shaped. Both of these cam followers are pivotally mounted on the previously described pintle 43, which is disposed between the posts 36, 31. Mounted on these follower arms intermediate their ends are cam follower pins 15a, 16a, which are rigidly secured to their respective arms and which project laterally therefrom to ride upon the periphery of the associated cam. The two follower arms are disposed on the outer sides of their respective cams; the arm 15 being disposed between the cam 6Id and the swinging arm 68 with its follower pin 15a projecting forwardly over the periphery of the cam Bld, and the arm 16 being disposed between the cam 6Ic and the swinging arm 69 with its' follower pin 16a projecting rearwardly over the periphery of the cam 6Ic. The hub ends of the two cam followers have coil springs associated therewith tending to swing these followers in wardly so as to hold their follower pins 15a, 16a resiliently pressed against the peripheries of their respective cams. The spring 18 associated with the follower 16 is illustrated in Figure 3, this spring having one end hooked over the outer or back edge of the follower 15 and having the other end bearing against pin 19, which extends between the mounting plate 26 and the bridge bar 4I. The other spring associated with the other cam follower is a duplicate thereof. The inwardly curved swinging end of each cam follower is provided with internal sector teeth which mesh with the pinion teeth of the associated swinging arms, Figure 3 illustrating these sector teeth 16h meshing with the gear teeth 68h, and it being understood that the other follower arm 15 has corresponding sector teeth 15b meshing with the pinion teeth 68h of its associated swinging arm. The pitch circle of these sector teeth has its axis at the pintle 43.

Itwilibeseenfromtheforegoingthatssthe month wheel and cam discs are given their intermittent angular motion with respect to the continuously revolving dial head, the cam follower.

pins'llo,1|aarecausedtoswinginwardlyand outwardly by the varying radii. of the cams against which they are continuously pressed by the springs Il. This inward and outward movement of the cam followers is transmitted to the swinging arms il, tl through the external and internal gear sectors represented at "b, 10b. Thus, the swinging arms and their switch actuators Il and i3 are caused to swing to different angular positions relatively to the dial head, as represented by the full line and dotted line positions illustrated in Figure 3. The aforementioned object of securing a constant ratio of motion transmission is clearly obtained by the above described relation of pinions and gear sectors, since, irrespective of whether either cam follower is at the outward, intermediate or inward positions of swinging motion, it is still transmitting rotative movement to its associated swinging arm at the same ratio. Accordingly, the design of the cams lid and llc is simpliiied. inasmuch as no compensation need be included in these cams for any varying ratio of motion transmission between the cam follower and the switch actuator. 'Ihe cam followers are always held pressed against the cams by the springs 'Il because the direction of rotation and general arrangement are such that the pressure of either switch actuator against its associated switch lever reacts to cause the follower pin 15a. 'Ila to be pressed inwardly against its respective cam with increased pressure. Consequently, there is no possibility of play or relative motion which might cause error.

The outer ends of the swinging arms Il, Il are provided with arcuate slots Il which receive the switch actuators Il, I3, and enable'the latter to be adjusted to dinerent angular positions with respect to each of their swinging arms. The actuator I2 is illustrated insection in Figure 4, from which it will be seen that it comprises a head Ila abutting the back side of the swinging arms and including a neck portion IIb having flattened sides which can slide in the slot Il but cannot rotate therein. A threaded shank i2c extends upwardly from this head and neck portion and receives a nut Ild having a reduced sleeve portion which abuts the outer side of the swinging arm. A roller ile is rotatably mounted on this reduced sleeve portion of the nut, and constitutes a rotatable bearing surface for contact- *ng with the associated switch arm I1. Releasing the nut ild enables the actuator I2 to be shifted to any desired position in the slot si, for advancing or retarding the time of switch actuation with respect to the position of the swinging arm 68. The other switch actuator II is similarly constructed and is similarly adjustable with respect to its swinging arm ls. Notches or other marks s2 may be provided adJacent to the slots tl for indicating the dierent positions of adjustment of the switch actuators.

A bridge plate Il is secured to the posts il, 81 end is provided with a corresponding arcuate slot Il' for receiving either the 03" switch actuator I3 or for receiving a switch actuator similar thereto. This bridge plate is disposed substantially in the same transverse plane as the swinging arm Il, so that any switch actuator mounted in the slot Il of this bridge plate will be effective to engage the switch lever il. The

purpoeeoftbisbridgepiateistoprovidefortbe adjustable mounting of a switch actuator which canbearrangedsothatitwillaiwaysopenthe switch Il at a selected hour around midnight. irresctiveofseasonalchangein thepositionof the "On" switch actuator II, or of the 01" switch actuator I8.

I claimzl. In time switch actuating mechanism. the combinationofstimecontrolledrotaryhead,a swinging arm mounted on said head and movable relatively thereto, a switch actuator carried bysaidarm.acammcuntedonsaidheadand rotatable relatively thereto, means for causing rotationofsaidcamrelativelytcsaidhemasshaped cam follower having its upper end pivotailymounted on said rotary head. afollower member projecting from an intermediate portion of said follower and engaging with the outer. periphery of said cam, an internal gear sector within the curved portion 4of said J-shaped cam follower, and a pinion meshing with said gear sector and operatively connected with said swinging arm.

2. In time switch actuating mechanism. the combination of a time controlled rotary head. a cam carried by said head and movable relatively thereto. means f or causing movement of said cam relatively to said head, a cam follower cooperating with said cam, a swinging arm mounted on said head, means for transmitting motion from said cam follower to said swinging arm, a switch actuator carried by said swinging arm, and a guide bar iixedly secured to said rotary head and coacting with said swlnging'arm for guiding the swinging motion of the latter.

3. In time switch actuating mechanism. the combination of a time controlled rotary head, a cam carried by said head and movable relatively thereto, means 4for causing movement of said cam relatively to said head, a cam follower cooperating with said cam. a swinging arm mounted on said head. means for transmitting motion from said cam follower to said swinging arm, a switch actuator carried by said swinging arm. and a pair of spaced guide bars nxedly secured to said rotary head and dening therebetween a guideway through which the outer portion of said swinging arm extends.

4. In time switch actuating mechanism of the class described. the combination of a time controlled rotary dial head. a pair of switch actuating members movably supported on said dial head. a pair of cams rotatably mounted on said dial head, and mechanism for transmitting motion from said cams to said switch actuators, said mechanism comprising two cam followers pivotally mounted on the same pivot axis and operatively connected with said switch actuators.

5. In time switch actuating mechanism of the class described, the combination of a time controlled rotary dial head. a pair of switch actuators mounted on said head to rotate therewith and movable relatively to said head, a pair of cam followers pivotally mounted on said head. a pair of cam discs supported on said head to rotate therewith but being rotatable relatively to said head. said cam discs cooperating with said cam followers and being disposed in transverse planes between the transverse planes of said cam followers. means operatively connecting said cam followers with said switch actuators. and means for causing movement of said cam discs relatively to said dial head.

B. In time switch actuating mechanism of the class described, the combination of a time controlled rotary dial head, a pair of cams carried by said dial head to rotate therewith, said cams being rotatable relatively to said dial head, means for causing rotative movement of said cams relatively to said dial head, a pair of cam follower levers pivotally mounted on said dial head, one disposed forwardly of both of said cams and the other disposed rearwardly of both of said cams, said levers having projections riding on the peripheral surfaces of said cams, spring means for yieldirmly holding said projections in engagement with said cams, a pair of swinging arms pivotally mounted on said dial head, one disposed forwardly of both cams and the forward cam follower lever and the other disposed rearwardly of both cams and of the rearward cam follower lever, means for transmitting motion from said cam follower levers to said swinging arms, and switch actuators mounted on said swinging arms.

7. In time switch actuating mechanism of the class described, the combination of a time controlled rotary dial head comprising a mounting plate and a mounting hub extending axially therefrom, a month wheel rotatably supported on said mounting hub, means for causing rotation of said month Wheel relatively to said dial head, a pair of j cams connected with said month wheel to rotate therewith, a pair of cam followers pivotally mounted on said head and cooperating with said cams, a pair of switch actuators movably mounted on said head, means for transmitting motion from said cam followers to said switch actuators, a dial plate on the outer side of said mounting plate, said dial plate having designating indicia inscribed thereon, and means removably securing said dial plate to saidmountlng plate enabling said dial plate to be substituted by a different dial plate having' diiferent designating indicia thereon. 8. In time switch actuating mechanism, the combination of a time controlled rotary head, a switch actuator associated with said head and movable relatively thereto, a cam associated with said head and movable relatively thereto, said switch actuator and said cam being concentrically mounted with respect to each other, means for causing movement of said cam relatively to said head, a pivot mounted on said head, a cam follower mounted on said pivot for pivotal movement with respect to said head and cooperating with said cam, and gear mechanism for directly transmitting a constant ratio of motion from said cam follower to said switch actuator.

9. In time switch actuating mechanism, the combination of a time controlled rotary head, a movable member carried by said head and mov-4 able relatively thereto, a switch actuator carried by said movable member, a cam associated with said head and rotatable relatively thereto, said movable member and said cam being concentrically mounted with respect to each other, means for causing motion of said cam relatively to said head, a pivot mounted on said head, a cam follower mounted on said pivot for pivotal movement with respect to said head and cooperating with said cam, and cooperating gears carried by said head for directly transmitting a constant ratio of motion from said cam follower to said movable member.

10. In time switch actuating mechanism, the combination of a time controlled rotary head, an arm mounted on said head for swinging motion relatively thereto, a switch actuator carried by said arm, a cam carried by said head and rotatable relatively thereto about the axis of said head, said arm and said cam being concentrically mounted with respect to each other, means for causing rotative movement of such cam relatively to said head, a cam follower cooperating with said cam, and mechanism including a cooperating pinion and sector directly carried by said arm and said cam follower respectively for directly transmitting a constant ratio of motion from said cam follower to said arm.

11. In time switch actuating mechanism of the class described, the combination of a time controlled rotary dial head, two swinging arms carried by said head and movable relatively thereto, switch actuators carried by each of said swinging arms, two cams mounted on said head and rotatable relatively thereto, said arms and said cams all being concentrically mounted with respect to each other, means for causing rotation of said cams relatively to said head, a single pivot mounted on said head, a pair of cam followers mounted upon said single pivot for pivotal movement with respect to said head, means yieldingly urging said cam followers into cooperation with said cams, gear sectors directly carried by said cam followers, and pinions meshing with said ,gear sectors and directly carried by said swinging arms for directly actuating said arms at a constant ratio of movement.

FREDERICK C HOLTZ. 

